Question

Write the formula for each molecular compound. a. boron tribromide b. dichlorine monoxide c. xenon tetrafluoride d. carbon tetrabromide

Short answer

a. BBr3, b. Cl2O, c. XeF4, d. CBr4

Step-by-step solution

Identify the Prefixes and Elements - Boron Tribromide

Determine the number of atoms and the elements present. For boron tribromide, 'tri-' means three and refers to the number of bromine (Br) atoms. There is no prefix before boron (B), which implies one boron atom.

Write the Formula - Boron Tribromide

Write down the chemical symbol for boron, which is 'B', followed by the chemical symbol for bromine, 'Br', then add the subscript '3' after 'Br' to indicate three bromine atoms: BBr3.

Identify the Prefixes and Elements - Dichlorine Monoxide

Recognize the prefixes and elements involved. 'Di-' means two and refers to chlorine (Cl) atoms. 'Mono-' means one and refers to oxygen (O) but the prefix mono is often omitted when it's the second element.

Write the Formula - Dichlorine Monoxide

Combine two chlorine atoms with one oxygen atom. Write 'Cl2' for chlorine, followed by 'O' for oxygen without a subscript: Cl2O.

Identify the Prefixes and Elements - Xenon Tetrafluoride

The prefix 'tetra-' indicates four, which refers to the number of fluorine (F) atoms. Xenon (Xe) is a noble gas and does not need a prefix when it's one atom.

Write the Formula - Xenon Tetrafluoride

Write the chemical symbol for xenon 'Xe' followed by the chemical symbol for fluorine 'F' with the subscript '4', indicating four fluorine atoms: XeF4.

Identify the Prefixes and Elements - Carbon Tetrabromide

The prefix 'tetra-' signifies that there are four bromine (Br) atoms. Carbon (C) is the other element and only one atom is present, so no prefix is needed.

Write the Formula - Carbon Tetrabromide

Write 'C' for carbon followed by 'Br' for bromine with the subscript '4', which means four bromine atoms are present: CBr4.

Key concepts

Chemical Nomenclature

Understanding chemical nomenclature is crucial to writing chemical formulas. It's a standardized system for naming chemical substances based on their composition and structure. For instance, the compound 'boron tribromide' follows a specific naming convention. In this case, 'boron' is the name of the first element, and 'tribromide' combines the prefix 'tri-' (meaning three) with 'bromide,' the name of the second element, bromine. This indicates the compound contains one boron atom bonded to three bromine atoms.

Similar patterns follow for other compounds like 'dichlorine monoxide' and 'xenon tetrafluoride'. Prefixes such as 'mono-', 'di-', 'tri-', and 'tetra-' tell us the number of atoms of each element in the compound. By knowing these conventions, we can both name compounds from their formulas and write formulas from their names. It is important to remember that sometimes, like with 'monoxide', the prefix 'mono-' is omitted if it refers to a single atom of the second element in a binary compound.

Chemical Symbols and Subscripts

Chemical symbols and subscripts are the alphabet of chemistry's language, allowing us to translate complex information about elements and their quantities into concise chemical formulas. For example, the chemical symbol for boron (B), followed by the symbol for bromine (Br) with a subscript of '3', creates the formula 'BBr3' for boron tribromide. The subscript number indicates how many atoms of the preceding element are present in the compound. If no subscript is shown, as with the 'B' in 'BBr3', it implies just one atom of that element.

It's essential to use these subscripts correctly to convey accurate information about a compound's composition. Misplacing or omitting a subscript can change the compound's identity entirely. Additionally, when writing chemical formulas, the symbols and subscripts should represent the real stoichiometric ratio of the atoms within the compound, reflecting the true nature of the molecular structure.

Molecular Compounds

Molecular compounds are substances formed by the combination of two or more nonmetals, bonded together through covalent bonds, where the electrons are shared between atoms. These compounds typically have low melting and boiling points and exist in various states of matter at room temperature – gases (like CO2), liquids (such as H2O), or solids (like S8).

The formulas for molecular compounds, such as xenon tetrafluoride (XeF4) or carbon tetrabromide (CBr4), reveal the exact number of each type of atom within a single molecule. The prefixes in their names provide insight into their composition, while the chemical symbols and subscripts consolidate that information into a structured representation. By learning about molecular compounds, students gain a deeper understanding of how atoms interact to form more complex structures, which is integral to the study of chemistry and the reaction processes.